﻿Report 
  oe 
  the 
  Botanist. 
  63 
  

  

  ceous-brown, 
  live 
  to 
  ten-septate, 
  .002'-. 
  0036' 
  long, 
  includ- 
  

   ing 
  the 
  very 
  short 
  concolorons 
  peduncle. 
  

  

  Leaves 
  of 
  soapwort, 
  Saponaria 
  officinalis. 
  Greenbush. 
  

   September. 
  

   The 
  spores 
  are 
  often 
  longer 
  than 
  the 
  flocci. 
  

  

  Nematogonum 
  aurantiacum 
  Desm. 
  

  

  Cut 
  surface 
  of 
  a 
  birch 
  stump. 
  Lake 
  Pleasant. 
  August. 
  

  

  Peronospora 
  obliqua 
  Cooke. 
  

  

  Living 
  leaves 
  of 
  yellow 
  dock, 
  Pumex 
  crispus. 
  North 
  

   Greenbush, 
  October. 
  

  

  Peronospora 
  Geranii 
  n. 
  sp. 
  

  

  Effused, 
  sometimes 
  occupying 
  the 
  whole 
  under 
  surface 
  

   of 
  the 
  leaf, 
  whitish, 
  the 
  flocci 
  irregularly 
  branched, 
  branches 
  

   short, 
  divaricately 
  spreading, 
  the 
  apices 
  not 
  swollen, 
  fur- 
  

   nished 
  with 
  short 
  slender 
  spicules 
  ; 
  acrospores 
  globose, 
  

   .0006' 
  in 
  diameter. 
  

  

  Living 
  leaves 
  of 
  Geranium 
  maculatum. 
  North 
  Green- 
  

   bush. 
  June. 
  

   Related 
  by 
  its 
  spiculose 
  branches 
  to 
  P. 
  gangliformis. 
  

  

  Erysiphella 
  nov. 
  gen. 
  

  

  Perithecia 
  destitute 
  of 
  appendages, 
  spores 
  definite. 
  

  

  This 
  genus 
  differs 
  from 
  Perisporium 
  in 
  having 
  a 
  definite 
  

   number 
  of 
  spores 
  in 
  an 
  ascus, 
  and 
  from 
  Uhcinula, 
  Micros- 
  

   phcera 
  and 
  Erysiplie 
  in 
  being 
  destitute 
  of 
  appendages. 
  

  

  Erysiphella 
  aggregata 
  n. 
  sp. 
  

  

  Mycelium 
  obscure 
  or 
  concealed 
  ; 
  perithecia 
  numerous, 
  

   densely 
  crowded, 
  subglobose, 
  glabrous, 
  reddish-brown 
  or 
  

   black 
  ; 
  sporangia 
  numerous, 
  ten 
  to 
  twenty, 
  varying 
  from 
  

   oblong-ovate 
  to 
  subclavate 
  ; 
  spores 
  eight, 
  broad, 
  elliptical, 
  

   .0008'-.0009' 
  long, 
  .0005'-.0006' 
  broad. 
  

  

  Fertile 
  aments 
  of 
  alders. 
  North 
  Greenbush. 
  May. 
  (Plate 
  

   2, 
  figs. 
  1-3.) 
  

  

  The 
  perithecia 
  are 
  densely 
  aggregated 
  in 
  the 
  interstices 
  

   of 
  the 
  aments, 
  giving 
  them 
  a 
  compact 
  blackened 
  appear- 
  

   ance. 
  Usually 
  a 
  white 
  meal-like 
  substance 
  more 
  or 
  less 
  

   involves 
  and, 
  with 
  the 
  crowded 
  perithecia, 
  conceals 
  the 
  

   mycelium. 
  Sometimes 
  nearly 
  all 
  the 
  aments 
  in 
  a 
  cluster 
  

   are 
  covered 
  by 
  this 
  fungus. 
  

  

  